Multiple plunger lift



Nav. 1, 1932. c. sTUKENBoRG MULTIPLE PLUNGER LIFT Filed Feb. 24. 1930Ufa/iwf Nov. 1, 1932. l.. c. sTuKENBoRG MULTIPLE PLUNGER LIFT 2Sheets-Sheet 2 Filed Feb. 24, 1930 di! :fe/Mar -Lazzf Jia/remar ya?C//a/weyf atented New., l, i932 intenta LOUJIS U. ST'UKEIQ'BORG, OFMMPHIS, TENNESSM, ASSIGNOR T0 STANDARD 'LIFT COMPANY, OF MEMPHIS,TENNESSEE, A CORPORATION 0F DELAWARE MULTIPLE IPLUNGER LEFT applicationmea rebruaw 24, i930. serial np. ascesa.

An object of my invention is to provide a lift for busses and otherlarge vehicles, the lift being of the multiple plunger type and beingcomparatively simple and durable and (g1 inexpensive to manufacture.

A further object is to provide a lift consisting of a vehicle supportwith a plurality of `lift devices such as those of the hydraulic typefor lifting the lvehicle support7 each lift device being 4preferablysecured to the vehicle support for raising the same.

A further Objectis to provide a means for synchronizing the motion ofthe plurality of lift devices regardlessof the weight distribution onthe vehicle support, such synchronizing means being of a mechanicalnature for positively insuring equal travel of each of the lift devicesto prevent buckling or twisting of the vehicle support. l

A further object is to provide in a multiple Aplunger lift having anotor for each lifting device, a safety means to prevent overloading ofone or more of the motors so as to preventdamage to the motors due tooverloading the vehicle support and distributing the weight a on thesupport in an exceptionally uneven way.

Still a further object is to provide a series of plunger lifts with amotor for each lift and an overload relay for each motor, the relays`being so connected that all of the motors are thrown out 4of circuitwhen any one of them is overloaded. v

With these and other objects in view. my invention consists in theconstruction, arrangement and combination of the various parts of mydevice, whereby the objects contemplated are attained, as hereinaftermore fully set forth, pointed out in my claims and illustrated in theaccompanying drawings. Although the invention is susceptible of avariety of embodiments, it is unnecessary to fully describe andillustrate more than one in order to give a full understanding of theinvention both from its structural and functional standpoints.Accordingly, I have ilment of the invention in the accompanying drawingsin which:

Figure 1 is a plan view of a multiple plunger lift embodying myinvention.

Figure 2 is a sectional view of the same on the line 2 2 of Figure 1. i

Figure 3 is a vertical sectional view on an enlarged scale and taken onthe line 3 3 of Figure 2.

Figure 4 is a sectional view on the line 1 -ll: of Figure 3.

Figure 5 is an electricaldiagrammatical gg@ View of the lift motors andcontrolling cir- .cuit therefor.

Figure 6 is a sectional view through an overload relay for one of themotors as taken on the line 6-6 of Figure l and Figure 7 shows afragmentary part of Figure 6 with the parts in a dierent position.. s

0n the accompanying drawings l have used the reference numeral 10 toindicate the to siderails of a vehicle support. rlhe rails l0 are oiisubstantial length for coaction with a long vehicle such as a motor bus.A plurality of lift devices each including a cylinder l2 and a plungerla are associated with the te side rails 10 for lifting them.

A head 16 is secured to each plunger 1d and extends between the siderails 10. 'llhe heads 16 are connected with the side rails by means ofcap screws 18 (see Figure 3)or may be ec welded to the side rails asdesired.

The specic construction of the lifting (levices is set forth in detailin my co-pending application Serial Number 366,889, filedy May 29, 1929.riefly each lift device includes a e@ partition 20 in the plunger 14 towhich an oil pump 22 is secured. 'llhe oil pump 22 yis adapted uponoperation to draw oil through a strainer 24 from the interior of theplunger 14 which constitutes an oil reservoir and dis- @u charge itthrough an opening 26 below the partition 26. A shaft 28 extends fromthe pump 22 to an electric motor 30 mounted in the top of the plunger14. Upon operation of the motor 30, oil will be pumped fromthe top @5 ofthe partition 20 to the cylinder 12 below the partition for raising thesupporting rails lustrated a preferred and desirable embodi- 10 When itisudesired to lower the supporting rails, oil may be released from belowthe parm@ tition to the reservoir space above the partition by opening anormally closed release valve 32 located in each plunger 14.

vA rod 34 extends upwardly from each release valve 32 and is adapted tobe engaged by a pivoted arm 36 which Iin turn is operated by a rockshaft 38 and handle 40. Thus it lil will 'be seen that when the releasevalves 32 are opened, the weight of the lift will force oil from belowthe partitions 20 to the reser- ,voir spaces above the partitions.

seat for the differential of thebus. The -re-y maining angles on thisplate are for reinforcing purposes. An adjustable seat for thedifferential is provided in the form of cross bars 46 and angles 48welded together. This device is sldable with respect to the side rails10. Stepped castings 50 may be provided for the front axle of the busand these are preferably connected together with a tie rod 52. Thisdevice is also slidable longitudinally with respect to the side rails10.

When more than one plunger is used in a lift of the character hereindisclosed, the

problemof.- causing all of the plungers 14 to move with equal speed andto equal heights is involved. The problem must be especially overcomewhere the weight distribution of the vehicle on the side rails 10 isuneven. In the present instance I have provided for synchronization ofall of the plungers 14 in the matter to now be described. .Y

A rack bar 54 is secured adjacent each head 16 of the plungers 14 to oneof the side rails 10"as best shown in Figure 3. A casing-56 is providedfor each rack 54 and may be supported relative to the cylinder 12 bymeans.

of encircling bands 58 and clamp bolts 60 and 62. A pair of bearingbrackets 6'4 is secured to each cylinder 12 as best shown in Figure 4and the rack bar 54 extends between these brackets. A pinion 66 vismounted between the brackets and secured to a stub shaft 68. The stubshafts 68 are. connected by` couplingr members 70 with intermediateshafts 72. The pinions 66 mesh with the rack bars 54 whereby it will beobvious that a movement of any one of the rack bars 54 will causecorresponding movement of the other rack bars and consequent equalmovement of all'the lift plungers 14.

A roller 74 mounted on a stub shaft 7 6 serves to maintain the rack barsin mesh with the pnions. A cover 7 8 is provided for each pinion. A. pitis provided extending longitudinally with respect to the lift and theintermediate shafts 72 as well as the pinions 66 and associatedmechanism are located in this it which may be suitably covered asdesired A drainv pipe.82 is provided for the pit 80.

Lesesaal In connection with eachlmotor 30 I provide a relay switchindicated. generally by the reference character A. In connection withall the motors a main switch B and a manually operable starting andstopping switch C is provided. Each relay switch A includes a pair ofcontacts 84 held in closed position by cams 86 which in turn are held inthe position shown in Figure 6 by thermolstatic strips 88. Heating coils90 are provided or exing the thermostatic strips 88 to the dotted lineposition'(or the full line position shown in Figure 7) whereupon theresilient contact strips 84 will spring apart as shown in Figure 7. Areset cord 92 is prpvided for each relay switch and these cords extendover pulleys 94 and are connected with a-reset cord 96. The reset cord96 may be connected with a bracket 98 adjacent the switch C'forconvenience of the operator in resetting the overload relays. l

The main switch consists of a plurality of switch arms 100 coactablewith contacts 102 upon an armature 104 being drawn toward an electromagnet 106. The manually operable starting and stopping switch Cincludes a starting button,108 and a stopping button 110. The button 108is held in extended position by springs 112 and contacts with anarmature arm 114 when pressed inwardly.

The stopping button 110 is connected with the armature 114 which is heldnormally in. one position by aspring 116. An electro magnet 118 isprovided for holding the armature 114 in on position after the button108 has been pressed.

Practical operation In the operation of my device when it is desired toactuate the lift for raising a vehicle,

the button 108 is pressed which establishes a circuit from a supply wire120 through the button 108, the button 110, the electro mag'- nets 118and 106, all of the contacts 84 of the relay switches A and back througha supply wire 122. The electro magnet 118 will then .hold the stoppingbutton 110 closed even after the starting button 108 is released. Thecurrent from the wire 120 will then iow through the right hand switch100 and through the stopping button 110 due to the pull of the electromagnet 106 on the armature 104 so that the starting button I108 when released does not break the circuit.

The pull of electro magnet 106 on the armature 104 will also close theleft and center switch arms 100 'for establishing a circuit through allo the motors 30. f

If the load is so distributed that it is `greater on one motor than onanother, then the other motors @through the rack bar and pinioninterconnections) will assist the loaded motor. In event that one .motoroverloaded to lo enferheatedS im i itil@ ticular relay A to iex it willcause the heatin coils of its pare thermostat stri s 88 and open theelectric circuit throught e electro magnets 106 and 118 whereupon themain switch will be opened by the spring 124 lfor cutting off thecurrent supply to all of the motors 30 and the armature 114 will bereleased in the switch C to restore this switch to normal position.After conditions have been adjusted for proper operation of the lift,the reset cord 96 may be pulled for resetting the relay which was openedby the overload.

Some changes may be made in the c`onstruction and arrangement of theparts of my device without de arting from the real spirit and purposes omy invention, and it is my intention to cover by my claims, any modifiedforms of structure of use of mechanical equivalents, which may bereasonably included within their scope.

I claim as m invention:

1. In a multiple plunger lift, a plurality of cylinders and a pluralityof plungers constituting lift devices, a vehicle support to be lifted byall of said devices and an operative connection between said plungersfor synchronizing their lifting motion regardless of the Weightdistribution on the vehicle support, said operative connectioncomprising a bracket supported on each cylinder, an

equalizer shaft journalled in said brackets, a rack bar movable witheachv lunger and each adjacent one of said brac ets and an equalizerpinion meshing with each rack bar and connected with said equalizershaft.

2. In a multiple plunger lift, a plurality of cylindersl and a pluralityof plungers constituting lift devices, a vehicle support to be lifted byall of said devices and an o erative connection between said plungers orsynchronizing their lifting motion regardless of the weight distributionon the vehicle support, said operative connection com rising a bracketsupported on each cylin er an equalizer shaft journalled in saidbracixets a rack bar movable with each lunger and each adjacent one ofsaid brac ets, a rack bar casingv supported on each cylinder forencasing said rack bars and an equalizer pinion meshing with each rackbar and connected with said e ualizer shaft.

LOUI C. STUKENBORG.

